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eFAST

Background

Although Anesthesiologists and trainees are typically involved in airway assessment and management when called to the trauma bay, it can be helpful to have the requisite skills to perform eFAST in resource-limited settings. Additionally, having the ability to assess for intra-abdominal free fluid can prove useful to investigate suspected bleeding in post-surgical patients. The eFAST exam should be used to answer binary questions (Does this patient have a pneumothorax? Is there free fluid in the abdomen? Does this patient have a pericardial effusion?)

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Indication

  • Unstable trauma patients

  • Trauma patients with thoracic or abdominal trauma

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Acquisition

Transducer: Phased array (allows for better visualization of cardiac structures)

 

Patient Position: Supine​

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Operator Mechanics

  • Operate probe with dominant hand 

  • Place ultrasound machine on same side as operator to manipulate controls with non-dominant hand

  • This may mean that right-handed operators are reaching over to patient’s left side

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Scanning Technique

  • There are multiple approaches to the sequence of the eFAST examination

    • Targeted sequence based on mechanism of injury (i.e. start with lung views if thoracic trauma)

    • Caudad to cephalad approach to avoid missing components

 

Cardiac (Subcostal Four Chamber) View

  • Refer to module on cardiac POCUS

  • Indicator marker convention is opposite normal cardiology convention

    • Indicator marker for eFAST is directed to patient’s right

  • Probe is placed first on the upper abdomen just caudad to the ribs

  • Apply pressure to the abdomen and fan the probe to direct cephalad towards the patients left shoulder, attempting to find a window through the liver to view all four heart chambers

Right Upper Quadrant (RUQ) View

  • Probe is placed on the right side of the abdomen just posterior to the mid-axillary line at the 10th or 11th intercostal space with indicator marker directed cephalad

  • Identify the interface between the liver and right kidney (Morrison’s pouch)

    • This potential space is a common area for free fluid to collect in the abdomen (ie. hemoperitoneum) 

  • Scan anterior to posterior to identify any fluid collections, ensuring that the diaphragm, the tip of the liver, and both poles of the kidney are identified

  • Trendelenburg positioning can increase sensitivity

Left Upper Quadrant (RUQ) View

  • Probe is placed on the left side of the abdomen at the posterior axillary line at the 8th or 9th intercostal space with indicator marker directed cephalad

  • Identify the interface between the spleen and diaphragm (left subphrenic space)

    • This potential space is a common area for free fluid to collect in the abdomen

  • Scan anterior to posterior to identify any fluid collections, ensuring that the diaphragm, spleen, and both poles of the kidney are identified

Pelvic View

  • Longitudinal view​

    • Probe is placed in the centre of the abdomen just cephalad to the symphysis pubis with indicator marker directed cephalad

    • Rock probe caudad 

    • The bladder is used as a window to observe free fluid

    • Differences in male and female anatomy will be apparent

      • Free fluid tends to collect in the rectovesical pouch and rectouterine pouch (Pouch of Douglas)

    • Fan the probe left and right to identify that lateral borders of the bladder

  • Transverse view​

    • From the longitudinal view, rotate the probe 90 degrees so that the indicator marker is directed to the patient’s right

    • Fan the probe cephalad to caudad to identify the superior and inferior borders of the bladder

Transverse Bladder

Longitudinal Bladder

Lung Views (Left and Right)​​

  • Refer to module on lung POCUS

  • Place probe on superior-anterior chest between ribs 2 and 3 examining both sides of the chest 

  • Indicator marker is directed cephalad

  • Identify lung sliding (motion of the visceral and parietal pleura with respiration)​

  • If present, shimmering image of the pleural line, often described as ants marching

  • If lung sliding is not readily apparent, put ultrasound into M-mode with beam centred between rib spaces

    • Seashore sign (picture) = + lung sliding - three distinct layers are apparent

      • Motionless superficial skin and soft tissue = sky (horizontal lines)

      • Motionless muscular layer = ocean (horizontal lines)

      • Sliding lung tissue = beach (sandy appearance)

    • Barcode sign (picture) = no lung sliding

      • All three layers are motionless - gives off the appearance of a barcode

Lung Sliding

Pearls

  • Exam should be complete in less than 5 minutes and should focus on identification of:

    • Abdominal free fluid

    • Pericardial fluid

    • Pneumothorax

  • Can occur at the same time as other assessment and investigations

  • If subcostal cardiac views are suboptimal, can view the heart in parasternal long axis

  • Perform pelvic ultrasound ideally with a full bladder, which may involve delaying foley catheterization or instilling 200 mL of saline into the bladder

Medical Decision Making

  • Pneumothoraces can be easily treated with chest tubes at the bedside

  • Numerous algorithms exist to direct patients to the operating room or CT scanner with variability between institutions

  • The following is a commonly followed algorithm 

    • Unstable patient, negative eFAST → CT scanner

    • Unstable patient, positive eFAST → operating room

    • Stable patient, negative eFAST → serial examination and eFAST

    • Stable patient, positive eFAST → CT scanner

Pitfalls and Modifications

  • People with internal reproductive organs can have a trace amount of physiologic pelvic free fluid, which may confound examination

  • eFAST may be especially useful in avoiding CT scans in pregnant patients, underscoring the importance of skill with this exam

  • There is a high rate of false-negative findings in pediatric patients, so eFAST should be used cautiously when making decisions about CT scans

Comprehension Questions

1. In the RUQ view, what are you looking for?

     A. Hydronephrosis

     B. Hepatorenal fluid

     C. Hepatomegaly

     D. Lung sliding​

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2. In the lung views, what are you looking for?

     A. Lung sliding

     B. Hemothorax 

     C. Chylothorax

     D. Rib fractures

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3. Which cardiac view do we obtain in eFAST scans?

     A. Subcostal Four-Chamber

     B. Apical Four-Chamber

     C. Parasternal Long

     D. Parasternal Short

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4. How long should an eFAST scan take?

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5. What three questions are we trying to answer with eFAST?

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Answers

1. B

2. A

3. A

4. 5 minutes maximum

5. 

  • Is there free fluid in the abdomen?

  • Does the patient have a pericardial effusion?

  • Does the patient have a pneumothorax?

References

Bloom, B. A., & Gibbons, R. C. (2021). Focused Assessment with Sonography for Trauma. In StatPearls. Retrieved May 1, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK470479/. 

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Pariyadath, M., & Snead, G. (2021). Emergency ultrasound in adults with abdominal and thoracic trauma. In UpToDate. Retrieved May 1, 2022, from https://www.uptodate.com/contents/emergency-ultrasound-in-adults-with-abdominal-and-thoracic-trauma

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Richards, J. R., & McGahan, J. P. (2017). Focused assessment with sonography in trauma (FAST) in 2017: What radiologists can learn. Radiology, 283(1), 30–48. https://doi.org/10.1148/radiol.2017160107 

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White, S., Dinh, V., Ahn, J., Deschamps, J., Genobaga, S., Lang, A., . . . Krause, R. (n.d.). EFAST Ultrasound Exam Made Easy: Step-By-Step Guide. Retrieved from https://www.pocus101.com/efast-ultrasound-exam-made-easy-step-by-step-guide/#eFAST_Algorithm_and_Summary

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